Cloth, and method for manufacturing a cloth

ABSTRACT

A cloth comprising a woven wire cloth covering an extended cloth area wherein said wire cloth has a uniform, low-reflective surface in that it consists of oxidized filaments, and a method for manufacturing a cloth.

The present invention relates to a low-reflective cloth and a method formanufacturing such a cloth. Low-reflective cloth types have been knownin the prior art where wire cloth is treated by electroplating tosuitably manipulate and configure the surface. A galvanic coating may beapplied so as to reduce the reflectivity characteristics of the cloth.

One drawback of such electroplated cloths is that the galvanic coatingis applied only in open, accessible places. The contact points of warpand weft wires will not be plated.

It is therefore the object of the invention to provide another cloth andanother method for manufacturing a cloth which has overall asubstantially uniform and low-reflective surface.

This object is achieved according to the invention by a cloth having thefeatures of claim 1. The inventive method is the subject matter of claim17. Preferred specific embodiments and configurations are the objects ofthe subclaims.

The cloth according to the invention comprises a woven wire clothcovering an extended cloth area. The wire cloth has a uniform,low-reflective surface in that at least part of it consists of oxidizedfilaments.

The invention has numerous advantages. It is a great advantage that thecloth filaments are oxidized since this allows a uniform, low-reflectivesurface. Surface conditions are equal on the filament surfaces as wellas at and near the individual contact points of the warp with the weftfilaments. This will make the reflection characteristics of the wirecloth generally homogeneous and uniform. Other structures may showlocally different characteristics in the vicinity of the individualfilament contact points.

It is another very great advantage that the cloth is not limited tospecific dimensions. For example for a cloth being surface-coated byelectroplating the cloth section sizes are limited by the size of theelectroplating tanks. The invention, however, employs surface-treatedfilaments for manufacturing the cloth such that the material can bemanufactured in rolls.

It is another advantage of the invention that contamination of or damageto the material during the electroplating process is prevented. Theelectroplating process requires special electroplating tanks. Since forreasons of cost-effectiveness most electroplating tanks are used forelectroplating a variety of objects, there is the risk that fine wirecloths are contaminated through particles present in the electroplatingsolution. This requires extensive cloth cleaning after electroplating.Contamination may even make a cloth entirely useless. These conceivabledrawbacks are avoided by the invention.

The wire cloth filaments consist substantially of metal and they arepreferably wires. Preferably said filaments or wires are monofilaments.Specific embodiments may provide that at least some filaments consist atleast partly of multifilaments. Said multifilaments may comprise twistedyarns and/or metal fiber yarns and/or strings and/or strands or beconfigured as such.

More specific embodiments of the invention provide for all of thefilaments to consist in particular at least partially and preferablysubstantially of steel, in particular stainless steel. The filamentspreferably consist of stainless steel, so-called high-quality steel. Thefilaments may preferably consist of acid-resisting and/oralkali-resisting steel.

High-quality steel filaments are very advantageous since they withstandhigh stresses and allow permanent use even in difficult conditions andwith aggressive media.

In preferred specific embodiments at least some, in particularsubstantially all of the wire cloth filaments have a diameter oftypically smaller than 100 μm. The typical diameters of the warpfilaments and/or the weft filaments are in particular smaller than 100μm. It is conceivable to use warp filaments and weft filaments ofdifferent diameters.

Preferred more specific embodiments provide in particular for the clothto be employed as a screen printing cloth. In preferred specificembodiments of the invention the typical cloth wire filament diameter isin particular smaller than 60 μm. The typical diameter may be smallerthan 50 μm, thus being approximately 30 μm or 25 μm or even as small as18 μm. In particular with screen printing cloths this will allow veryfine screen textures. This is often desired for printing electricalcircuits since fine or minuscule conductors must be manufactured.

For configurations with fine filaments it is preferred to weave a highnumber of meshes per length unit. Thus these weaves show a number ofmeshes per inch of length, or within 25.4 mm, of at least 100. It isparticularly preferred to have a number of meshes within one inch ofcloth length of 150 or 200 or higher. For example with screen printingcloths the number of meshes may be 300 or higher.

Other embodiments provide a number of meshes per inch of length at leastin one direction greater than or equal to 40.

It is preferred to employ or configure such a cloth as a protectingcloth. The number of meshes per inch of length in such applications isin particular smaller than 150 and in particular smaller than 100.Preferred number of meshes for protecting cloths per inch of cloth areapprox. 40 to approx. 80.

In other embodiments at least some of the wire cloth filaments have adiameter of typically larger than 500 μm. A typical diameter may inparticular be in the range of 1 or 2 millimeters or larger.

In these cases the mesh number or the number of meshes within one inchof length is preferably at least in one direction smaller than 5 and itmay be equal to or smaller than 1.

In such embodiments the cloth according to the invention may inparticular be employed as a wire cloth for architecture. The dull effectof the cloth can also be obtained in processing the wires in that fordrawing some or all of the wires a dry drawing agent is used so as toobtain a low-reflective surface.

In all of the embodiments and more specific embodiments of theinvention, filaments having a dark surface are preferred. The colorbrown is in particular preferred. Other colors are also conceivable suchas blue or red or golden hues. This depends on the manufacturing andtreatment conditions.

In preferred embodiments at least some of the filaments are synthetic.The cloth can then entirely be a hybrid cloth of synthetic and metalthreads. The synthetic fibers may consist of monofilaments ormultifilaments.

The synthetic fibers may be woven into the cloth in addition to themetal threads. They then serve in particular for strengthening orreinforcing the cloth. The synthetic fibers may be arranged to be evenlydistributed over the cloth surface or over individual cloth areas.

It is also conceivable to provide an overall or in particular locallyuneven distribution of the synthetic fibers over the cloth surface. Forexample—for cloth or sections to be used for example as screen printingcloth—strengthening may occur by framing the print area with syntheticfibers.

The wire cloth is in particular configured and structured so as to besuitable to be clamped in with a clamping force of at least 20 N per cmcloth edge. The wire cloth is in particular configured to be used atclamping forces of 25 N/cm or 30 N/cm or higher. With screen printingcloths in particular the wire cloth is mounted on a frame and thentensioned at the desired clamping force. Wire cloth furnishes amongother things the advantage of higher stressability than woven syntheticfibers. Moreover, wire cloth does not require re-tensioning butpermanently retains the fixed clamping force.

This is an advantage in particular for screen printing cloths since thesubstantially stable clamping force allows fine screen printing wherethe printing precision does not deteriorate with increasing age of thescreen printing cloth. Therefore such a screen printing cloth is inparticular suited for printing circuits.

In this respect the invention also relates to screen printing cloth andto using a cloth as a screen printing cloth. The screen printing clothaccording to the invention comprises a woven wire cloth covering anextended cloth area having a substantially uniform and low-reflectivesurface. This is achieved in that the cloth consists of oxidizedfilaments at least in part.

The invention also relates to protecting cloth and to using a cloth as aprotecting cloth. The protecting cloth according to the inventioncomprises a woven wire cloth covering an extended cloth area having asubstantially uniform and low-reflective surface. This is achieved inthat the cloth consists of oxidized filaments at least in part.

The protecting cloth serves to shield from radiation emitting inparticular from electrical devices. The protecting cloth may beconfigured in accordance with one of the embodiments described above.The protecting cloth is in particular provided to be employed withelectrical or electronic devices or X-ray apparatus or other apparatusemitting harmful or interfering radiation.

With medical electrical apparatus for example it must be guaranteed thatthe electromagnetic radiation generated will not affect other medicalequipment as stray radiation. For this purpose one may employ aprotecting cloth applied inside the apparatus and possibly mounted infront of visible areas. The mounted protecting cloth must not hinder theuser's view and therefore a low-reflective cloth is used. The clothaccording to the invention is suitable for this purpose of reliablyprotecting from radiation while affecting the visual impression to aminimal extent.

Furthermore the invention also relates to wire cloth for architectureand to using a cloth as a wire cloth for architecture. The wire clothfor architecture according to the invention in turn comprises a wovenwire cloth covering an extended cloth area having a substantiallyuniform and low-reflective surface. This is achieved in that the clothconsists of oxidized filaments at least in part.

The invention also relates to a method for manufacturing a cloth with awoven wire cloth covering an extended cloth area wherein first at leastpart of the filaments or wires for manufacturing said wire cloth arepurposely oxidized and only thereafter woven.

The inventive method also offers considerable advantages. Pretreatmentof the filaments or wires of the wire cloth allows to manufacture auniform, low-reflective cloth. The cloth sizes are not limited tospecific tank dimensions but they can be chosen as desired since thecloth can be manufactured as a continuous material.

The treatment of the wires allows a homogeneous surface configuration ofthe individual filaments so as to guarantee a uniform, low-reflectivewire cloth surface even in tight wire cloth areas.

Preferred more specific embodiments of the method according to theinvention provide for the filaments or wires to be annealed. The wiresare in particular conveyed through a furnace for heating the filaments.To this end, a volume flow of a gas mixture is supplied in the furnaceor at or in front of the furnace.

The gas mixture preferably consists at least of at least one inert gasand furthermore comprises gaseous water. The gaseous water serves inparticular as an oxidizer for the wire surfaces.

In order to enrich the inert gas, which may include a number of inertgas components, with water vapor, at least part of the volume flow ofthe inert gas is preferably passed through a container with a waterreservoir. Within said container, vaporous water is added to the volumeflow. This process may be enhanced by atomizing liquid water. Or elsethe inert gas may be passed through a water bath where it absorbs watervapor.

The preferred inert gas employed is nitrogen. Argon or another inert gasmay also be used.

Inside the furnace a measure for the humidity of the gas mixture ispreferably determined by means of a humidity measuring means. Preferablythe humidity, i.e. the water vapor content, of the gas mixture iscontrolled. This occurs preferably by using the humidity measuring meanssignal and in dependence thereon adjusting the water vapor supply.

The water vapor content may in particular be influenced through theliquid water temperature in the water reservoir. The temperature in thewater reservoir is therefore preferably controlled.

It is furthermore advantageous to control the temperature and/or thevolume flow and/or the ambient pressure of the inert gas or the gasmixture.

It is furthermore preferred to control the conveying speed of the wiresthrough the furnace.

Furthermore the furnace temperature is preferably controlled. Preferredembodiments may provide a furnace temperature of 1100° C. In a preferredembodiment the wires may for example be heated to values of approx. 600°C., 800° C. or 1000° C. or higher.

After heat treatment the wires or filaments are preferably coated withan agent to allow better handling during weaving. After weaving thecloth is preferably cleaned. This is for removing, among other things,any remaining coating agent residue.

Further features, properties and advantages of the present inventionwill be understood from the following description of embodiments inconjunction with the attached drawing.

It shows in:

FIG. 1 a schematic view of a cloth according to the invention.

FIG. 1 is a highly schematic illustration of a first embodiment of aninventive cloth.

The cloth 1 according to the invention comprises a wire cloth 2. Thecloth can be mounted on a—not shown—frame. FIG. 1 illustratesexemplarily a number of warp wires 11 to 18 and a number of weft wires21 to 26 of the wire cloth 2. These filaments or wires 11 to 18 and 21to 26 are high-quality steel.

The cloth 1 represented in FIG. 1 is a plain weave. In otherembodiments, other types of weave may be used. Aside from twilled orsatin twilled weave, any other types of weave may be used in the clothaccording to the invention. In particular for use as a wire cloth forarchitecture for covering building facades, inner and outer walls, oropen air passages or other structures, the cloth according to theinvention may have other types of weave to exhibit the desired strengthproperties and to achieve an attractive optical effect.

The surface 3 of the wires was oxidized by the method according to theinvention before weaving. This occurs by annealing the wires in afurnace. The conveying speed of the wires is adjusted such that thewires reach the required temperature. To manufacture low-reflectivewires from the bright high-quality steel wires, an inert gas containinga defined proportion of water is introduced into the furnace.

The volume flow of the gas mixture is adjusted at a defined value.

With the high temperatures of up to 1100° C. or higher present in thefurnace the water vapor acts as an oxidizer, scaling the wire surfaceswhich thus lose their shine and change their color.

The furnace temperature may be employed to influence the surface qualityof the wires leaving the furnace. The wires reach temperatures of e.g.approx. 980° C. to 1000° C. The temperatures may be lower and inparticular considerably lower. The adjusted temperature depends on thedesired results, e.g. the surface color is thus related to thetemperature. The color hue may be set in dependence on a number ofparameters to obtain e.g. blue, brown, golden or red hues.

The temperature and the other conditions will result in a correspondingstructure of the surface 3 of the wires.

For low-reflective screen printing cloth, a brown color will as a rulebe set. The same applies to protecting cloth, the so-called shieldingcloth, for shielding radiation.

The water vapor is only allowed to enter in low concentrations; thewater vapor molecule concentration may thus be a few ppm (parts permillion) or a few tens of ppm. The inert gas employed may e.g. benitrogen enriched with water vapor. Enriching may for example occur innormal ambient temperatures such that only a little water vapor isabsorbed. A small portion of water vapor is already sufficient toreliably and reproducibly effect scaling.

The water proportion is controllable. A humidity sensor may be providedin the supply line for the gas mixture in front of the furnace or evenin the gas mixing device and dependent on the result the inert gastemperature or pressure can be adjusted.

Since the wires—in particular for screen printing cloth—may be extremelyfine, at diameters 5 in the region of e.g. approx. 100 μm down toapprox. 20 μm, supplying pure oxygen would oxidize the entire wire. Thewire could no longer be woven then. It is therefore imperative to treatonly the surface 3 of the wires to guarantee further processability andthe function. The physical properties essential for weaving aresubstantially not affected in the negative.

A number of meshes 6 per length unit is selected depending on theapplication. As a rule, the number of meshes is indicated per inch oflength (mesh count). For screen printing cloth for printing circuits themesh count can be increased up to 250 and even above 300. With a meshcount of 254, there are as many as 10 wires per millimeter. If the wiresare not intended to be tightly packed, given a mesh count of 254 thewire diameter should be smaller than 100 μm. A typical wire diameter ise.g. 30 μm.

The free areas 7 between the wires serve to apply material to the groundin a screen printing process.

The wire clearance 4 between the wires may be in the range of the wirediameter 5 or it may be a multiple thereof.

With protecting or shielding cloth for shielding radiation e.g. ofmonitors, the mesh count will as a rule be smaller, being betweenapprox. 40 and 80.

1. A cloth, comprising a woven wire cloth covering an extended clotharea, said wire cloth including oxidized filaments to provide a uniform,low-reflective surface.
 2. The cloth of claim 1, wherein the filamentsare made of high-quality steel.
 3. The cloth of claim 1, wherein atleast some of the filaments have a diameter of smaller than 100 μm. 4.The cloth of claim 1, wherein the wire cloth has a number of meshes perone inch of length of greater than or equal to 40 at least in onedirection.
 5. The cloth of claim 4, wherein the number of meshes per oneinch of length is greater than
 100. 6. The cloth of claim 1, wherein atleast some of the filaments have a diameter of larger than 500 μm. 7.The cloth of claim 1, wherein the wire cloth has a number of meshes perone inch of length of smaller than 5 at least in one direction.
 8. Thecloth of claim 1, wherein the filaments have a dark surface.
 9. Thecloth of claim 1, wherein the wire cloth is configured for clamping at aclamping force of at least 20 N per cm of cloth edge.
 10. The cloth ofclaim 1, wherein at least some of the filaments are synthetic.
 11. Thecloth of claim 10, wherein the synthetic filaments are evenlydistributed in the wire cloth.
 12. The cloth of claim 10, wherein thesynthetic filaments are unevenly distributed in the wire cloth.
 13. Thecloth of claim 1, for use as a screen printing cloth.
 14. The cloth ofclaim 13, for printing circuits.
 15. The cloth of claim 1, for use as aprotecting cloth.
 16. The cloth of claim 1, for use as a wire cloth forarchitecture.
 17. A method for manufacturing a cloth with a woven wirecloth covering an extended cloth area, comprising the following sequenceof steps: oxidizing a desired number of wires of a plurality of wiresand weaving the plurality of wires to produce a wire cloth.
 18. Themethod of claim 17, wherein the oxidizing step includes the step ofsubjecting the wires to an annealing process by passing the wiresthrough a furnace in the presence of a volume flow of a gas mixture. 19.The method claim 18 wherein the gas mixture includes inert gas andgaseous water.
 20. The method of claim 18, wherein at least part of thevolume flow is passed through a water reservoir.
 21. The method of claim18, further comprising the step of measuring a humidity of the gasmixture.
 22. The method of claim 18, further comprising the step ofcontrolling at least one parameter selected from the group consisting oftemperature, volume flow, and ambient pressure of the gas mixture. 23.The method of claim 20, further comprising the step of controlling atemperature of the water reservoir.
 24. The method of claim 17, whereinthe oxidizing step includes the step of controlling a conveying speed ofthe wires.